It’s the rebirth of a classic. Rovio announced on their blog today that they’ve published a new version of Angry Birds for Windows Phone that adds 100 new levels—for more than 400 in all. The Windows Phone 8 version also sports Xbox LIVE achievements and leaderboards. The game is free through May 15.

As the blog post notes, this new version is a completely separate download from the one that you might already have on your phone. “The reason why we’re re-releasing the game is that it will be technically easier for us to support in the future, so we’re really happy to get this out there!” Rovio writes.

The new version is also designed to work on Windows Phone 8 models with 256MB of memory.

Downloading the new version of the game won’t affect your progress in the old one. You can continue to play both. But it’s worth grabbing the improved one while it’s free for the extra levels and any future ones Rovio decides to spring on its fans.

And speaking of future releases—I’m hearing that that Angry Birds Rio is on the way for Windows Phone “very soon.”